At Goldladder, we have been scoring some fairly big SEO ranking hits recently in a quest to ensure duplicate content is purged from websites. The Farmer algorithm updates in Google have made this work even more important. Rel=canonical has been at the heart of this approach (along with some good tag discipline in WordPress etc), so its nice to see Matt Cutts explaining how Google works with Rel=canonical. Matt Cutts on Rel Canonical and 301 redirects